US1512261A - Propeller-shaft bearing - Google Patents

Description

@cm 21, 924. mm2@ E.ALLEN\ `PROPEIJLER SHAFT BEAR I NG Filed Feb. 17. 192] m gm Patented Oct. 21, 1924.

UNITED STATES EDWARD ALLEN,VOCF JERSEY CITY, NEW JERSEY.

PROPELLER-SHAFT BEARING.

Application led February 17, 1921. Serial No. 445,697.

To all whom t may concern.'

Be it known that I, EDWARD ALLEN, a

'resident of Jersey City, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Propeller-Shaft Bearings, of 'which the following is a specification.

This invention relates to improvements in stern tube bearings for propeller shafts, and is'directed more especially to means for sealing the ends of such tubes.'

y t is the usual practice to house out board or tail propeller shafts within a stern tube provided interiorly with longitudinally extending stri s of lignum vitae, which space the shafts rom the tubes and provide a smooth bearing for the former in the outer portion of the latter. The after ends of 4such tubes are ordinarily left open, permitting the sea water to enter between the strips` and circulate thruout theV lengths thereof, particularly when they have become worn. This is doneupon the assumption that the water will assist in lubricating the shafts rubbing on' the strips, keep down friction and carry olf the heat generated. Besides in view of the fact that salt water in particular has a deterimental corrosive effecten the shafts, `the same are generally linedl or surrounded by endwise abutting brass or bronze sleeves.

The construction above noted is not only expensive, but allows sand and grit to work into the ends of the stern tubes, especially when operating in shallow waters, where the screw or propeller stirs up the sea or river vbottom. The action is most* pronouncedwhen the rotation of the screw fis/reversed, since backward turning of the vpropeller manifestly throws the muddy water directly against the after end ofthe stern tube and causes the sand and grit to find their way in between the bearing strips and the 'shaft liners. y.

The presenceof grit among these parts,

rapidly wears them out so that after a while the propellershaft lworks so loosely that it is'practically unsupported at the aft4 end thereof, causing it to 'sa at the tail portion. This' condition is mani ested by the knocking or thumpin sound'often heard at the stern of a pro er driven steamer.

When a 'tall shaft is operated without i fr'lProPer SuPPOTt as 9 result of the wear referred to, whipping of the shaft ensues, and the strains oasioned thereby are so severe ing of the shaft.

screw boat working in heavy seas, at which that they ultimately cause fracture or break- In the case of a single times such accidents generally occur, the breakage of a propeller shaft is apt to have serious consequences, since the vessel then loses headway and becomes unmanageable.

Furthermore, the sagging or bending of the shaft has the effect of opening up the joints between the liners or sleeves allowing the sea water to attack and cause pitting of the shaft. This deleterious condition is accentuated by electrolytic action taking place between the steelshaft and the copper alloy of the liners, particularly when they are subjected'to the influence of salt water.

In order to keep the sea water that has enteredj the stern tube; from leaking thru the inner endthereof, a stuing box packed with hemp is mostly used for this purpose. But as such packing generally becomes hard when exposed to salt water and loses its flexibility, the stuing box gland has to be tightened up frequently. This forces the sti-ffened packing still harder against the surface of the shaft, which thru continued usage is badily cut or scored thereby.

The present invention aims to obviate the above enumerated diiculties, asalso others, and the main or primary object thereof is to provide an effective seal for the ends of a propeller shaft bearing or stern tube, which will prevent the entrance thereinto ofmuddy or grit-carrying water, as well as retain thereinthe substance employed to lubrcate the shaft.

Another object is to produce a device of the character described wherein .the lubric'ant used has free access to the working surfaces of the stern bearing thruou't the entire stern tube iscontrolled by a lubricant sup-I plied from within the vessel.

Still anotherl object .in the production of i -a device of the typespecied is to dispense with the liner sleeves'jheretofore aociated withv tail shafts of pro llers, as well as to avoid their attendantzdlisadvantages, and to accomplish this result without exposing such tube may not-be increased materially beyond shafts to the corrosive action of sea water.

A. still further object in producing a device of the class mentioned 1s so to arrange the co-operating members thereof that the overhang of the propeller from the stern what is accepted in common practice.

An additional object is to procure a device of the species referred to entirely devoid of springs, and so constructed that the coacting 'elements are self-adjusting without undue pressure thereon and will retain a tight running fit for the propeller shaft while obviating scoring or cutting of the same.

A general object is to supply a device of the genus alluded to composed of a minimum number of parts, simple, durable and amenable to low cost of manufacture, as also expeditiously assembled or dismantled, besides capable of being readily applied to existing stern tubes without appreciable alteration thereof.

Other obects and advantages of the invention will become apparent as the 'specification proceeds.

With the aforesaid objects in view, the invention consists of the novel combinations and yarrangements of arts hereinafter described in' their pre erred embodiments, pointed out in the subjoined claims, and illustrated on the annexed drawing, wherein like parts are designated by the same reference characters throughout the several views.

In the said drawing:

Figure I is a sectional elevation of a part of the stern of a Ipropeller driven vessel showing the usual tubular bearing thereof with this improved sealing device applied to the ends of-the same;

Fig. H is an enlarged end view of an element forming part of the present device;

'.Fig. HI is a similar view of another elei ment employed in this construction;

Fig. lV is a like view, of an additional element adapted to be associated with the one illustrated in Fig. lll; and

Figs. V and VI are transverse sections on the lines V-V-andVll-Vll respectively, of Fig. ll.

Succinctly outlined, the device under consideration includes in its organization a cap membersecured in any appropriate manner to either end of the usual stern tube which houses the propeller tail shaft. rllhe cap that is attached to theoutboard end of the stern tube is provided with a boss adapted to extend into and bereceived in a recess formed in the adjacent face of the hub of the propeller,` the rshaft of the latter passing thruv the cap and its boss with a snug turning t. Seated within the cap, spaced from the end of the `tube, is a follower element" A tting around the shaft relativelytight and part, while both of them bear against the inside head-of the cap member. rlhe construction is such that the more the outer part is forced out endwise, the harder the inner part will grip the shaft so as to prevent any leakage between the latterpthe cap and the parts themselves.

Lubricant preferably heavy grease, is introduced under pressure into the stern tube` by any suitable means, such as a force-feed grease-cup, and caused to fill up the interstices between the bearing strips and the bushings. The pressure of the lubricant exerted upon the follower forces the latter against the inside head of the cap and effects a seal therewith so that very little or no lubricant can pass the same, nor between the periphery of the follower and the cap. 'llhe grease thus supplied, not only lubricates the shaft and the stern bearings, but in its attem t to find an exit thru the closure at the a ter end of the tube, automatically operates to eect'a seal for the same and precludes the entrance of sea' water thereinto. In practice, a small amount of the lubricant may work its way out, but the loss thereof is negligible.

rlhe member at the inboard end of the stern tube comprises a discoidal plate, ,hollowed out to receive the follower element which is driven and acts in 'a manner similar to that at the outer extremity of the tube. This plate or retaining member may be held in its assigned 4position by the 'same bolts that were used to draw up the gland against the packing in the stuiing box. lDueI to this construction no scoring or cutting of the shaft can occur at the place mentioned, and the lubricant is also pre-vented from leaking out. rlhe space formerly occupied by the packing will constitute a reservoir for the grease which will fill the same. Thus it wil be seen that the entire part` of the tail pro` peller shaft housed within the stern tubf runs in a bath of grease which in its turn prevents the entrance of water into the former. l

The advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined in the one and samestructure, but, useful devices may` be produced embodying less than the whole.y p

It will be obvious to lthoseskilled in the art to which the invention appertains, upon becoming conversant with the details thereof, that-the same may `be incorporated in several different constructions. The accompanying drawing, therefore, is submitted 1,51a,ae1

with which the same are associated have been designated by reference letters, of which A denotes the stern post of a vessel, which post has theusual rearwardly extending frame B forming therewithin the propeller well C.

From a point interiorly of a bulkhead D there runs in a fore and aft direction thru' the stern post, the stern tube E, the outer vextremity whereof terminates within the propeller well. The said stern tube is necked down as at E1 so as to provide a shoulder E2 arranged to abut the forward edge of the stern post. The necked down portion of the tube E reaching within the well C is furnished with a threaded part E3 adapted to receive a n'ut E4 wherewith the shoulder E2 can be firmly drawn up against the stern post.

Near its inner end, the stern tube is formed with a flange E5 thru which it is supported from the bulkhead D, being secured thereto as by screw bolt Ee.- At the innermostextremity, the stern tube has as ordinarily is the case, a flange E7 from which project stud bolts E8 adapted to retain in position the customary stu'ling box gland (not shown).

In conformity with current practice, and varying more or less, according to circumstances, approximately one-half the length of the interior 'of the stern tubes inboard portion is provided with brass or bronze bearing-bushings E10' within which is journalled the propeller tail shaft F. The remaining part of the latter which is not carried by these bushings, is instead supplorted by a plurality of hardwood strips 11, such as lignum vitae. These strips eX- tend longitudinally of the tube E and are fastened therearound as 'b dove-tail connections E12, best seen in Flg. V. The said strips E11 are shaped complementary to the cross-sectional contour of the shaft 'and enl gage the rear end thereof so as tol form a continuous bearing.

The propeller shaft F projects beyond the after end of the. stern tube, into the well- C and is tapered as at F1 to constitute a seat for a correspondingly shaped hole thru the hub of the pro eller G. This hub is keyed I'to the tapere i'n Figi.' I, and the parts'are forced solidly together by means .of a nut F2 which is threaded onto a reduced extreme portion Fsvofvthe shaft'and acts against an inter,- posed washer F1. Generally, the interstices in the outboard portion F1 of the shaft, and in the hub ofthe propeller, as also the conportion F1 as shownl tacting faces of the nut F? and washer F1, as well as the reduced part E1 of the tube with the shoulder E2 Aand therewith coacting nut E1, are coated and filled in with some such substance as heavy white-lead paint, to preclude corrosion.

Lubricant is introduced into lthe interior of the stern tube thru a pipe H which connects with the side of the former and leads to any convenient localitywithin the vessel, at which point. it. is provided with a force feed. grease cup H1, or other suitable means for applying pressure onto the grease. In alignment with the outlet. ofthe. pipe H, the bearing bushing E10 has one or more passages H? thru which the lubricant is directed against the shaft F. If desired, the innei surface of this bushing may also be formed with grooves to insure circulation of the grease and effect its traveling toward the stern of the boata Grease thus 'injected within the stern tube will entirely fill the same including the spaces'that may existbetween the strips E11, and' in this bath of lubricant the shaft revolves so that it will be properly lubricated at all times and friction reduced. i

VAs hereinbefore mentioned, the ends of the stern tube are Sealed each by a suitable mechanism which is preferably operable by the lubricant pressure within the tube to Ataining member has been represented as attached to the exterior of the stern tube, it is within the province of the present invention to secure the same in, any other appropriate way, y

The outer end of the 'cap member 15 is extended rearwardly to enclose that portion ofthe shaft F which would otherwise be exposed between the former and the adjacent face of the propeller hub. With this purpose in view the said c/ap has projecting therefrom a boss 18 bored as at 19 to let the shaft pass ltherethru and formed exteriorly so as to fit a complementary recess provided therefor in the forward end ofthe hub' of the propeller GL By this construction it will-be manifest that in spite of the factthat thel tail end of the pro eller shaft is mounted without the emp oyment of liners or external sleeves, as here tofore, sea water has no direct access thereto.

lll

sth

lnteriorly the cap 15 is hollowed out to constitute a cylindrlcal chamber 21 in which is adapted to be seated a follower element 22 of discoidal formation and having a bore 23 fitted to take over the shaft F, being rotated thereby preferably thru a key or spline connection. The latter is shown as consisting of a feather 24. carried by the shaft F and co-operating with a keyway 25 formed at'one side of the bore 21 in the follower. Thus, the element 22 is secured against rotation on the shaft, but adapted for slight movement longitudinally or axially thereof, which in the structure illustrated is between an inner head 26 of the reaining member 15 and the end ofthe stern tu e.

With this construction, it will be apparent that the pressure of the grease within the stern tube acts upon the follower 22, thereby causing it to be forced tightly against the head 26 which constitutes a seat therefor and includes both transverse and circumferential surfaces. The force with which the follower engages this seat will obviously be proportionate to the pressure of the lubricant in the tube. Accordingly, a seal will thus be effected which becomes better as the pressure of the grease increases, so that a relatively high pressure of the latter will not result in leakage at this point. However, to insure proper lubrication between the contacting surfaces of the follower and its seat, the former is preferably provided on its outer face with one or more circular grooves 27 which may be intersected by radial channels 28, and at the intersections of said grooves and channels, passages 29 are provided thru the follower in order to permit the grease to circulate and properly lubricate the parts. l

With the purpose of precluding leakage of the lubricant past the follower 22 and out thru the bore 19 of the boss 18, the after face of the said follower may be provided with an outwardly flared recess 31 in which is lodged a packing ring 32 preferably split diametrically into two halves that are ada ted, collectively to embrace the shaft F. 'l e periphery of this packing ring is'bevelled as at 33, andthe sections thereof which have a common bore .34 are forced together by the taper of the recess 31 and made to tightly clasp around the shaft. At 35 is indicated a keyway with which one of the ring'sections is provided and that is adapted to be engaged by the feather 24. By virtue of this arrangement both the follower 22 and itsI packing ring are positively rotated by the shaft aswell as axially movable'thereon, while the former are also in-` terrelatively self-adjusting. f f' The chief function of the packing ring I sections is to ac t as a barrier against straight thru ow of the grease. This maybe furdetails` thereof may @meer ther insured by providing the inside bores spectively. These grooves serve to catchl particles of grease, which in their turn prevent the sea ,water from passing the same. Such of the grease as may work past the groove 38, must find its way out between the boss 18 and the therewith coacting recess in the hub of the propeller, but the amount of grease which passes off' and is wasted is a negligible quantity.

The seal retainer at the inboard end of the stern tube E is here shown as consisting of a plate 15a of substantially discoidal contour. This plate may be held in its assigned position up against the hereinbefore mentioned flange E7 by the same stud bolts E8, that heretofore were used to keep the common-stuffing box gland in place. rllhe interior ofthe said plate 15a is hollowed out as at 21a to provide a chamber within which is contained a follower 22a driven by the forward end of the tail shaft F thru the instrumentality of a feather 24a, while free for limited longitudinal movement thereon. ln order to prevent the saidfollower 22'a from slippin back into the space formerly occupiedy the fibrous packing, this follower is made larger than the internal diameter of the stulhng boxordinarily located at this point. A split ring 32a wedgingly engaged by the follower 22a is lodged within a forward recess of the latter and participates in its movements, being adapted to preclude straight outflow of the lubricant at the stern tubes forward extremity. rllhe space immediately in rear of the follower 22 fills up with grease and serves as a reservoir therefor, whereby the main How is directed rearwardly. lit is obvious that the grease that may work its way out thru the forward seal 'can be recovered and used over again. It will be noticed that both the key-means 24 and 24a are located inwardly of the seats of their respective follower elements 22 and 22, the feather 24 being obviously disposed forwardly of the seat 26. v

From the foregoing it will be apparent that the seal for either end of the stern tube can be applied thereto without requiring changes of any appreciable character. lin racticing the Iresent invention any desired ubricant may e employed, such for exanr' ple as heavy oil or grease, and in the following claims, this lubricant is referred to generically as a duid.

Whilea certain preferred embodiment of this device has been shown and described,' it will be understood that changes in the form, arrangements, proportions, sizes and e made, without departing from the scbpe of the invention as defined by the a pended claims.

Having descri ted-my` invention what 1I desire to secure by Letters Patent and claim, 1s

1. A stern bearing for propeller shafts comprising in combination, a tube thru which the shaft passes provided with a closure forming a seat adjacent its outer end, an element associated with the shaft and said seat adapted to be impelled against the latter by fluid pressure within said tube to effect a seal precluding exit of the fluid or the entrance of sea water, key-means with the shaft capable of imparting coincidental rotation to said element, said key-means being disposed forwardly of the said seat so as to be protected thereby, and other means lfor introducing said fluid under pressure into the tube.

`2. A stern bearing for propeller shafts comprising in combination, a tube in which the shaft is housed, a member closing the after end of said tube having direct engage- 4ment with the shaft, an element driven by.

said shaft mounted thereupon, being also capable of movement toward or away from said member, and means for introducing a fluid under pressure into the tube to lubricate the parts and to force said element into engagement with the member to effect a seal against leakage of the fluid or the entrance of sea water.

3. A stern bearing for propeller shafts comprising in combination, a tube in which the shaft is journalled, a closure for the outer en'd of said tube including a fixed seat, an annular element composed of parts rotated together by said shaft while:V capable yof longitudinal movement thereupon, the

ends of both of said parts being normally in contact withv said seat, and means for introducing a lubricant under pressure into the'tube to lubricate the working parts and forcing said element against the closure in order to effect a tight seal preventing escape of the lubricant or the entrance of sea water.

4. A stern bearingfor propeller shafts comprising in combination, a tube thru which the shaft extends, a closure .for the after end of said tube, a recessed element driven by said shaft' axially movable thereupon toward or away from vsaid closure, packing means lodged in Said recess precluding leakage along the shaft, said pack-l ing means being also slidable 'upon and rotated by the latter, and means for introducing a fluid into the tube to lubricate the Working`parts and force said element into engagement with the closure to effect a seal against the exitv of the fluid or the entrance of sea water.

5. A stern bearing for vpropeller shafts comprising in combination, a tube thru which the shaft passes, the latter carrying the propeller which is provided in the forward face of its hub with a recess, and means vfixed to the end of said tube projecting into said recess in contact with the shaft to enclose the Isame.

6. A stern bearing for propeller shafts comprising in combination, a tube affording a lubricated bearing for the shaft, the latter carrying the propeller which is provided with a recess in the forward face of its hub, a closure for 'the after end of said tube attached thereto and having a boss taking over the shaft in position-to extend into said recess, and means associated with said closure precluding eXit of lubricantl from the interior of the tube-or entrance of sea water thereinto.

7. A sealing device for a propeller shaft stern tube. Vcomprising a retaining member provided with a recess affording a seat, in-

cluding transverse and circumferential surfaces, means for aiiixing said member endwise of said tube, a tightening element lodged in said recess and rotated directly by said shaft at the forward side of said seat and having a limited axial movement on the former, said element being in working engagement with both of said surfaces, and

means Within the tube'for holding the element against the seat.

8. A sealing device for` a propeller shaftstern tube, including a chambered retaining member having a seat, means for securing said member to the end of said tube, a recessed element lodged in the chamber of the said member and rotated by said shaft being free to move llongitudinally thereon relatively to said seat, a split packing ring contained in the recess of said element-1n position to rotate therewith in contact with the shaft, and means for pressing the conjoined element and packing 'ring against the seat to prevent leakage into or out of the tube.

9. A sealing device for a propeller shaft tube including a cap member secured to the latter, said member having a bore and rovided with a transverse seat, a r'st oo lar slidable in said bore against said seat over e the shaft, said collar being formed with an outwardly flaring recess facing the seat a second collar. ttedginto said recess, sai r second collar beingV split to enable the same to tighten itself upon the shaft when the first named collar is moved thereagainst, a key-element 'for imparting rotation to the coact'in-g collars from the shaft, and means within the tube acting to'v force the collars conjointly upon the seat in the member.

- EDWARD ALLEN.

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